There may well be an other way, and that's the one I employ here all the time: get a second-hander/hand-me-down and do an INSTALL on that one. Dont shoot me if I dont get the nubb here (it's four in the morning here...) but as the guru's mentioned, you seem to pop the DVD into the drive, do an
update/upgrade on that DVD and then -
bamm - run out of (what seems to you)
diskspace...
A Live medium (DVD/CD/USB stick/...) has the
memory as playground, in that memory a filesystem gets
imitated, as if on a physical disk. Try it, do a wget of something and observe that it landed in a folder, and that folder...exists in memory, nowhere else.
You could (as syg00 suggested) redirect the mountpoints, but it would get (as syg00 mentioned) get messy, as you'd end up with an "OS" that has a read only portion (the DVD) that it tries to upgrade. Besides that, this would inevitably flood your harddrive with bits-n-bobs that dont belong in your main OS...how messy (and
ugly) is that...
The option jefro popped up (using a USB stick) seems then more to your needs...but, these things are not really fomula one racers...
Eh, just my thoughts...
Thor